Как использовать Factory boy, когда два внешних ключа указывают на одну и ту же таблицу - PullRequest
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Как использовать Factory boy, когда два внешних ключа указывают на одну и ту же таблицу

0 голосов
/ 10 июня 2018

Я пытаюсь связать две модели Django, используя Factory Boy, но я не смог найти тривиальное решение для этой проблемы.Это модели с соответствующими заводами: 

class Currency(models.Model):
    id = models.CharField(max_length=3, primary_key=True)


class ConversionRate(models.Model):
    currency = models.ForeignKey(Currency, null=False, on_delete=models.CASCADE)
    quote = models.ForeignKey(Currency, null=False, on_delete=models.CASCADE)
    rate = models.DecimalField(max_digits=6, decimal_places=2)


class CurrencyFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Currency

    id = factory.Sequence(lambda n: ['EUR', 'USD'][n%2])
    conversion_rate = factory.RelatedFactory('my_app.factories.ConversionRateFactory', 'currency')


class ConversionRateFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = ConversionRate

    currency = factory.SubFactory(CurrencyFactory)
    quote = factory.SubFactory(CurrencyFactory, id='EUR')
    rate = 1.2

Это содержимое таблиц для тестирования по умолчанию: 

+--------+   +--------------------------+ 
|Currency|   |       ConversionRate     |
+--------+   +----------+--------+------+ 
|   id   |   | currency |  quote | rate |
+--------+   +----------+--------+------+ 
|  EUR   |   |    USD   |  EUR   |  1.2 |
+--------+   +----------+--------+------+  
|  USD   |   |    EUR   |  EUR   |   1  |
+--------+   +----------+--------+------+

При попытке построить фабрику выдается ошибка целостности: 

CurrencyFactory.create()
# Error:  UNIQUE constraint failed: Currency.id

Я также пытался добавить django_get_or_create = ('id',) в CurrencyFactory «Meta», но это создает бесконечный цикл.

Кто-то сталкивался с проблемойкак это в прошлом?Любое предложение?

Это обратная связь при использовании django_get_or_create = ('id',): 

    env/lib/python3.6/site-packages/factory/builder.py:272: in build
        step.resolve(pre)
    env/lib/python3.6/site-packages/factory/builder.py:221: in resolve
        self.attributes[field_name] = getattr(self.stub, field_name)
    env/lib/python3.6/site-packages/factory/builder.py:375: in __getattr__
        extra=context,
    env/lib/python3.6/site-packages/factory/declarations.py:324: in evaluate
        return self.generate(step, defaults)
    env/lib/python3.6/site-packages/factory/declarations.py:414: in generate
        return step.recurse(subfactory, params, force_sequence=force_sequence)
    env/lib/python3.6/site-packages/factory/builder.py:233: in recurse
        return builder.build(parent_step=self, force_sequence=force_sequence)
    env/lib/python3.6/site-packages/factory/builder.py:299: in build
        context=postgen_context,
    env/lib/python3.6/site-packages/factory/declarations.py:675: in call
        return step.recurse(factory, passed_kwargs)
    env/lib/python3.6/site-packages/factory/builder.py:233: in recurse
        return builder.build(parent_step=self, force_sequence=force_sequence)
    env/lib/python3.6/site-packages/factory/builder.py:272: in build
        step.resolve(pre)
    env/lib/python3.6/site-packages/factory/builder.py:221: in resolve
        self.attributes[field_name] = getattr(self.stub, field_name)
    env/lib/python3.6/site-packages/factory/builder.py:375: in __getattr__
        extra=context,
    env/lib/python3.6/site-packages/factory/declarations.py:324: in evaluate
        return self.generate(step, defaults)
    env/lib/python3.6/site-packages/factory/declarations.py:414: in generate
        return step.recurse(subfactory, params, force_sequence=force_sequence)
    env/lib/python3.6/site-packages/factory/builder.py:233: in recurse
        return builder.build(parent_step=self, force_sequence=force_sequence)
    env/lib/python3.6/site-packages/factory/builder.py:279: in build
        kwargs=kwargs,
    env/lib/python3.6/site-packages/factory/base.py:314: in instantiate
        return self.factory._create(model, *args, **kwargs)
    env/lib/python3.6/site-packages/factory/django.py:163: in _create
        return cls._get_or_create(model_class, *args, **kwargs)
    env/lib/python3.6/site-packages/factory/django.py:154: in _get_or_create
        instance, _created = manager.get_or_create(*args, **key_fields)
    env/lib/python3.6/site-packages/django/db/models/manager.py:82: in manager_method
        return getattr(self.get_queryset(), name)(*args, **kwargs)
    env/lib/python3.6/site-packages/django/db/models/query.py:487: in get_or_create
        return self.get(**lookup), False
    env/lib/python3.6/site-packages/django/db/models/query.py:394: in get
        clone = self.filter(*args, **kwargs)
    env/lib/python3.6/site-packages/django/db/models/query.py:836: in filter
        return self._filter_or_exclude(False, *args, **kwargs)
    env/lib/python3.6/site-packages/django/db/models/query.py:850: in _filter_or_exclude
        clone = self._chain()
    env/lib/python3.6/site-packages/django/db/models/query.py:1156: in _chain
        obj = self._clone()
    env/lib/python3.6/site-packages/django/db/models/query.py:1168: in _clone
        c = self.__class__(model=self.model, query=self.query.chain(), using=self._db, hints=self._hints)
    env/lib/python3.6/site-packages/django/db/models/sql/query.py:337: in chain
        obj = self.clone()
    env/lib/python3.6/site-packages/django/db/models/sql/query.py:300: in clone
        obj.where = self.where.clone()
    env/lib/python3.6/site-packages/django/db/models/sql/where.py:148: in clone
        children=[], connector=self.connector, negated=self.negated)

    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

    cls = <class 'django.db.models.sql.where.WhereNode'>, children = [], connector = 'AND', negated = False

        @classmethod
        def _new_instance(cls, children=None, connector=None, negated=False):
            """
                Create a new instance of this class when new Nodes (or subclasses) are
                needed in the internal code in this class. Normally, it just shadows
                __init__(). However, subclasses with an __init__ signature that aren't
                an extension of Node.__init__ might need to implement this method to
                allow a Node to create a new instance of them (if they have any extra
                setting up to do).
                """
    >       obj = Node(children, connector, negated)
    E       RecursionError: maximum recursion depth exceeded while calling a Python object

1 Ответ

0 голосов
/ 11 июня 2018

Как вы заметили, проблема заключается в CurrencyFactory создании ConversionRateFactory, которое, в свою очередь, создает 2 CurrencyFactory.

Я предлагаю использовать factory.Traitчтобы отключить его с помощью рекурсии:

  1. Определите черту в фабричном разделе class Params: при включении (установив логический флаг) он добавит прикрепленное объявление
  2. Установитьзначение по умолчанию True для этой черты: прямой вызов CurrencyFactory добавит ConversionRate
  3. . В ConversionRateFactory отключите черту - предотвращая запуск цикла.

См. Код ниже: 

class CurrencyFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.Currency
        django_get_or_create = ['id']

    class Params:
        with_conversion_rate = factory.Trait(
            conversion_rate=factory.RelatedFactory('my_app.factories.ConversionRateFactory', 'currency'),
        )

    # Small improvement: use a `factory.Iterator` to cycle between value
    id = factory.Iterator(['EUR', 'USD'])
    # By default, force each CurrencyFactory to create a ConversionRate.
    with_conversion_rate = True

class ConversionRateFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.ConversionRate

    rate = 1.2
    currency = factory.SubFactory(
        CurrencyFactory,
        with_conversion_rate=False,
    )
    quote = factory.SubFactory(
        CurrencyFactory,
        id='EUR',
        with_conversion_rate=False,
    )
...